Electric current could be produced in a wire by simply moving a magnet in or out of a wire coil.
Voltage was induced by the relative motion between a wire and a magnetic field.
The production of voltage depends only on the relative motion between the conductor and the magnetic field.
Voltage is induced whether the magnetic field of a magnet moves through a stationary conductor, or the conductor moves through a stationary magnetic field.
The amount of voltage induced depends on how quickly the magnetic field lines are traversed by the wire. This therefore means that very slow motion produces hardly any voltage at all and quick motion induces a greater voltage.
The greater the number of loops of wire that move in a magnetic field, the greater the induced voltage and the greater the current in the wire.
For example, pushing a magnet into twice as many loops will induce twice as much voltage and pushing it into ten times as many loops will induce ten times as much voltage.
When there are more loops, you cause more current to flow in a coil, and this makes the coul act as a more powerful electromagnet.
A coil with more loops is a stronger magnet and pushes back harder.
The amount of voltage induced depends on how quickly the magnetic field changes. Very slow movement of the magnet into the coil produces hardly any voltage at all. Quick motion induces a greater voltage.
Electromagnetic induction-inducting voltage by changing the magnetic field around a conductor.
37-2 Faraday’s Law
The induced voltage in a coil is proportional to the product of the number of loops and the rate at which the magnetic field changes within those loops
The amount of current produced by electromagnetic induction depends not only on the induced voltage but also on the resistance of the coil and the circuit to which it is connected.
37-3 Generators and Alternating current ·If one end of a magnet is plunged in and out of a coil of wire, the induced voltage alternates in direction. ·When the magnetic field strength inside the coil is increased, the induced voltage in the coil is directed one way and when the magnetic field strength diminishes, the voltage is induced in the opposite direction. ·A generator is a device that continuously rotates a coul of wire inside a magnetic field by faraday’s law as the amount the magnetic field passing through the coil. ·A generator is the opposite of a motor because a motor converts electric energy to mechanical energy and a generator converts mechanical energy to electric energy.
37-4 Motor and Generator Comparison
Moving charges experience a force that is perpendicular to both their motion and the magnetic field they transverse.
Deflected wire is the motor effect and the law of induction is the generator effect
An electric motor and a generator are effectively the same device, the difference is where the energy is put in and where the energy comes out.
A motor converts electrical to mechanical and a generator converts mechanical to electrical energy.
37-5 Transformers
Example: think of having two coils that are side by side in which one is connected to a battery and the other is connected to a galvanometer
The coil connected to the power source is the primary, input, and the other coil is the secondary, output.
The reason that there is only a small connection of current that passed through and when the primary switch is opened, current registers in the opposite direction, the magnetic field that builds up around the primary extends into the secondary coil.
A transformer is the rate at which the magnetic field changes in the primary is equal to the frequency of the alternating current.
It can be used to increase or decrease the voltage coming from an alternating current source.
The ratio by which the voltage will change is equal to the ratio of the number of turns on the output coul to the number of turns on the input coil
The equation is: power= (voltage * current) sub pri= (voltage* current) sub sec
37-6 Power Transmission
Most electric energy sold today is in the form of alternating current (ac) because of the ease with which it can be transformed from one voltage to another.
37-7 Induction of Electric and Magnetic Fields
Electromagnetic induction is used in terms of the construction of voltages and currents
Faraday’s law can be generalized to the case where there may not be a conductor in a changing electric field. It states:
“An electric field Is created in any region of space in which a magnetic field is changing with time. The magnitude of the created electric field is proportional to the rate at which the magnetic field changes. The direction of the created electric field is at right angles to the changing magnetic field.”
37-8 Electromagnetic Waves
When an electric current is present, it will create a magnetic field, but the changing magnetic field around a changing current will also create an electric field
If two field are arranged correctly the result will be electromagnetic waves which are changing electric and magnetic fields that move at the same speed and emphasize each other.
37-1 Electromagnetic Induction
37-2 Faraday’s Law
- The induced voltage in a coil is proportional to the product of the number of loops and the rate at which the magnetic field changes within those loops
- The amount of current produced by electromagnetic induction depends not only on the induced voltage but also on the resistance of the coil and the circuit to which it is connected.
37-3 Generators and Alternating current· If one end of a magnet is plunged in and out of a coil of wire, the induced voltage alternates in direction.
· When the magnetic field strength inside the coil is increased, the induced voltage in the coil is directed one way and when the magnetic field strength diminishes, the voltage is induced in the opposite direction.
· A generator is a device that continuously rotates a coul of wire inside a magnetic field by faraday’s law as the amount the magnetic field passing through the coil.
· A generator is the opposite of a motor because a motor converts electric energy to mechanical energy and a generator converts mechanical energy to electric energy.
37-4 Motor and Generator Comparison
- Moving charges experience a force that is perpendicular to both their motion and the magnetic field they transverse.
- Deflected wire is the motor effect and the law of induction is the generator effect
- An electric motor and a generator are effectively the same device, the difference is where the energy is put in and where the energy comes out.
- A motor converts electrical to mechanical and a generator converts mechanical to electrical energy.
37-5 Transformers- Example: think of having two coils that are side by side in which one is connected to a battery and the other is connected to a galvanometer
- The coil connected to the power source is the primary, input, and the other coil is the secondary, output.
- The reason that there is only a small connection of current that passed through and when the primary switch is opened, current registers in the opposite direction, the magnetic field that builds up around the primary extends into the secondary coil.
- A transformer is the rate at which the magnetic field changes in the primary is equal to the frequency of the alternating current.
- It can be used to increase or decrease the voltage coming from an alternating current source.
- The ratio by which the voltage will change is equal to the ratio of the number of turns on the output coul to the number of turns on the input coil
- The equation is: power= (voltage * current) sub pri= (voltage* current) sub sec
37-6 Power Transmission37-7 Induction of Electric and Magnetic Fields
37-8 Electromagnetic Waves